Any property, in this case the rewarding effect of acoustic stimuli in humans, can be powerfully maximized. There must exist patterns in music-space that would have profoundly greater impact on human minds than those our low-wattage brains can find. So through a really powerful search process (read: artificial general intelligence) that can more efficiently explore remote, undiscovered regions of music-space, we could get music-patterns more alluring and emotionally stimulating than any currently imaginable.
What these songs would sound like is the real mystery. Would they sound anything like the music we're familiar with? Would they lead to musical wireheading [0]?
It also seems a bad idea to measure musical goodness by, say, how many times humans will replay a certain audio file. If you use this measure, I don't think you'll end with what you want at all.
See also:
"Siren Worlds And The Perils Of Over-Optimised Search." [1]
[0] https://en.wikipedia.org/wiki/Wirehead_(science_fiction)
[1] https://www.lesswrong.com/posts/nFv2buafNc9jSaxAH/siren-worl...